Question from someone who doesn't use Linux much: Are package managers distro-specific, then?

Kind of. When you hear people say they use a "Debian based" distro they'll be using apt as their package manager.

You have 3 main "base" distros/package mamagers:

Debian/apt

RHEL/yum/dnf

Arch/pacman/pkgbuild

There are of course many more but these are the overwhelming majority.

This means if I wanted to make my own distro I could do as little as take Debian stable as my upstream, rebuild a few packages with a s/Debian/MyDisro/g and change a few default packages and call it that.

Or I could track a mix of packages from Debian testing and stable.

Or I could decide I prefer to build everything my self but still use apt for my package manager.

This is of course turtles all the way down eg: Mint is based of Ubuntu which is based of Debian.

Just nitpicking, but the package manager for the Debian family is dpkg, not apt; apt is a layer above dpkg. The same way, the package manager for the RedHat family is rpm; yum and it successor dnf is a layer above rpm.

Mint works correctly only with mintupdate.

If you do "sudo apt update && sudo apt -y dist-upgrade" then it breaks Mint desktop menu. To fix it, you can install all updates with mintupdate, and then "sudo apt -y install mint-menu --reinstall"

Package managers are one of the main things that define a distro. The big split is between packaging formats (DEB and RPM [0]) and then there are package managers for that for that (apt* for DEBs and yum, dnf, zypper etc. for RPMs [1]). You could run a foreign package manager on any distro, there even exist ones for that purpose [2], but it's ostensibly considered a defining feature for a distro.

[0] There are more of course, but those are the big two.

[1] I'm really only familiar with the Debian/Ubuntu space (Deb)

[2] See flatpak, snap, and nix/guix. Also some distros like Bedrock Linux let you have completely foreign environments mixing together.

> Are package managers distro-specific, then?

Technically no, effectively yes.

You can install and use different package managers on different distros, but with the exception of things like cargo it's highly recommended to not, as you are likely going to break your system.

For all intents and purposes, yes. Besides making software easy to install, package managers figure out all the dependencies that a given package requires and install those as well. Can you install yum/dnf on Debian? I'm sure there's a way to do it. But good luck handling all the dependencies for a given package. Plus, there will be file conflicts when dnf installs a base dependency that apt already installed.

In other words, nothing good comes from trying to install two different package managers on one system.

Yes. Package management is most of what a distro does.